diff --git a/components/p3a/features.cc b/components/p3a/features.cc
index 5f274cf196be..5d24169532f3 100644
--- a/components/p3a/features.cc
+++ b/components/p3a/features.cc
@@ -4,6 +4,7 @@
  * You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 #include "brave/components/p3a/features.h"
+#include "brave/components/p3a/metric_log_type.h"
 
 namespace p3a {
 namespace features {
@@ -14,6 +15,12 @@ BASE_FEATURE(kConstellation,
 BASE_FEATURE(kConstellationEnclaveAttestation,
              "BraveP3AConstellationEnclaveAttestation",
              base::FEATURE_DISABLED_BY_DEFAULT);
+BASE_FEATURE(kTypicalJSONDeprecation,
+             "BraveP3ATypicalJSONDeprecation",
+             base::FEATURE_DISABLED_BY_DEFAULT);
+BASE_FEATURE(kOtherJSONDeprecation,
+             "BraveP3AOtherJSONDeprecation",
+             base::FEATURE_DISABLED_BY_DEFAULT);
 
 bool IsConstellationEnabled() {
   return base::FeatureList::IsEnabled(features::kConstellation);
@@ -24,5 +31,12 @@ bool IsConstellationEnclaveAttestationEnabled() {
       features::kConstellationEnclaveAttestation);
 }
 
+bool IsJSONDeprecated(MetricLogType log_type) {
+  if (log_type == MetricLogType::kTypical) {
+    return base::FeatureList::IsEnabled(features::kTypicalJSONDeprecation);
+  }
+  return base::FeatureList::IsEnabled(features::kOtherJSONDeprecation);
+}
+
 }  // namespace features
 }  // namespace p3a
diff --git a/components/p3a/features.h b/components/p3a/features.h
index 4c0d61acf329..46b6a15e9463 100644
--- a/components/p3a/features.h
+++ b/components/p3a/features.h
@@ -7,6 +7,7 @@
 #define BRAVE_COMPONENTS_P3A_FEATURES_H_
 
 #include "base/feature_list.h"
+#include "brave/components/p3a/metric_log_type.h"
 
 namespace p3a {
 namespace features {
@@ -16,8 +17,15 @@ BASE_DECLARE_FEATURE(kConstellation);
 // See https://github.com/brave/brave-browser/issues/31718 for more info.
 BASE_DECLARE_FEATURE(kConstellationEnclaveAttestation);
 
+// See https://github.com/brave/brave-browser/issues/34003 for more info.
+// Disables JSON measurements for "typical" cadence.
+BASE_DECLARE_FEATURE(kTypicalJSONDeprecation);
+// Disables JSON measurements for all other cadences.
+BASE_DECLARE_FEATURE(kOtherJSONDeprecation);
+
 bool IsConstellationEnabled();
 bool IsConstellationEnclaveAttestationEnabled();
+bool IsJSONDeprecated(MetricLogType log_type);
 
 }  // namespace features
 }  // namespace p3a
diff --git a/components/p3a/message_manager.cc b/components/p3a/message_manager.cc
index ad4601490764..7993941a0d73 100644
--- a/components/p3a/message_manager.cc
+++ b/components/p3a/message_manager.cc
@@ -45,9 +45,11 @@ MessageManager::MessageManager(PrefService& local_state,
 
   // Init log stores.
   for (MetricLogType log_type : kAllMetricLogTypes) {
-    json_log_stores_[log_type] =
-        std::make_unique<MetricLogStore>(*this, *local_state_, false, log_type);
-    json_log_stores_[log_type]->LoadPersistedUnsentLogs();
+    if (!features::IsJSONDeprecated(log_type)) {
+      json_log_stores_[log_type] = std::make_unique<MetricLogStore>(
+          *this, *local_state_, false, log_type);
+      json_log_stores_[log_type]->LoadPersistedUnsentLogs();
+    }
     if (features::IsConstellationEnabled()) {
       constellation_prep_log_stores_[log_type] =
           std::make_unique<MetricLogStore>(*this, *local_state_, true,
@@ -86,11 +88,13 @@ void MessageManager::Init(
       config_.get());
 
   for (MetricLogType log_type : kAllMetricLogTypes) {
-    json_upload_schedulers_[log_type] = std::make_unique<Scheduler>(
-        base::BindRepeating(&MessageManager::StartScheduledUpload,
-                            base::Unretained(this), false, log_type),
-        config_->randomize_upload_interval, config_->average_upload_interval);
-    json_upload_schedulers_[log_type]->Start();
+    if (!features::IsJSONDeprecated(log_type)) {
+      json_upload_schedulers_[log_type] = std::make_unique<Scheduler>(
+          base::BindRepeating(&MessageManager::StartScheduledUpload,
+                              base::Unretained(this), false, log_type),
+          config_->randomize_upload_interval, config_->average_upload_interval);
+      json_upload_schedulers_[log_type]->Start();
+    }
   }
 
   rotation_scheduler_ = std::make_unique<RotationScheduler>(
@@ -128,9 +132,9 @@ void MessageManager::UpdateMetricValue(
     constellation_prep_log_stores_[log_type]->UpdateValue(
         std::string(histogram_name), bucket);
   }
-  if (update_for_all || !*only_update_for_constellation) {
-    json_log_stores_[log_type].get()->UpdateValue(std::string(histogram_name),
-                                                  bucket);
+  auto* json_log_store = json_log_stores_[log_type].get();
+  if ((update_for_all || !*only_update_for_constellation) && json_log_store) {
+    json_log_store->UpdateValue(std::string(histogram_name), bucket);
   }
 }
 
@@ -139,9 +143,9 @@ void MessageManager::RemoveMetricValue(
     absl::optional<bool> only_update_for_constellation) {
   bool update_for_all = !only_update_for_constellation.has_value();
   for (MetricLogType log_type : kAllMetricLogTypes) {
-    if (update_for_all || !*only_update_for_constellation) {
-      json_log_stores_[log_type]->RemoveValueIfExists(
-          std::string(histogram_name));
+    auto* json_log_store = json_log_stores_[log_type].get();
+    if ((update_for_all || !*only_update_for_constellation) && json_log_store) {
+      json_log_store->RemoveValueIfExists(std::string(histogram_name));
     }
     if (features::IsConstellationEnabled() &&
         (update_for_all || *only_update_for_constellation)) {
@@ -153,7 +157,10 @@ void MessageManager::RemoveMetricValue(
 
 void MessageManager::DoJsonRotation(MetricLogType log_type) {
   VLOG(2) << "MessageManager doing json rotation at " << base::Time::Now();
-  json_log_stores_[log_type]->ResetUploadStamps();
+  auto* log_store = json_log_stores_[log_type].get();
+  if (log_store) {
+    log_store->ResetUploadStamps();
+  }
   delegate_->OnRotation(log_type, false);
 }
 
@@ -185,11 +192,13 @@ void MessageManager::OnLogUploadComplete(bool is_ok,
   } else {
     log_store = (metrics::LogStore*)json_log_stores_[log_type].get();
     scheduler = json_upload_schedulers_[log_type].get();
+    CHECK(log_store);
     if (is_ok) {
       delegate_->OnMetricCycled(json_log_stores_[log_type]->staged_log_key(),
                                 false);
     }
   }
+  CHECK(scheduler);
   if (is_ok) {
     log_store->MarkStagedLogAsSent();
     log_store->DiscardStagedLog();
@@ -257,6 +266,8 @@ void MessageManager::StartScheduledUpload(bool is_constellation,
     log_store = json_log_stores_[log_type].get();
     scheduler = json_upload_schedulers_[log_type].get();
   }
+  CHECK(log_store);
+  CHECK(scheduler);
 
   if (!is_constellation &&
       base::Time::Now() -